RAW files are processed using the ACS calibration software, CALACS, to perform
standard calibrations such as bias and dark subtraction, as well as flat-fielding, to create calibrated
products called FLT files. Note that these images have not yet been corrected for geometric
distortion.

For ACS/WFC data taken after SM4 data, CALACS corrects artifacts due to post-SM4 electronics,
a signal-dependent "bias shift" and bias striping.

All WFC data undergoes pixel-based CTE corrections, resulting in calibrated FLC files where
CTE trails are removed and lost charge is restored to sources.

FLT files are processed by AstroDrizzle to create geometric distortion-corrected images, DRZ files.
FLC files are similarly processed to create DRC files. If the FLT or FLC data are
part of an association, the images are drizzle-combined; otherwise, individual FLT or FLC
exposures are drizzled.